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(No Model.)

G. G. SWAN.

INCANDBSGENT LAMP.

No. 516,689. Patented Mar. 20, 1894.

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UNITED STATES PATENT OFFICE.

GEORGE C. SVVAN, OF BROCKTON, MASSACHUSETTS, ASSIGNOR OF TWO- FIFTIIS TOFREDERICK C. RUSSELL, OF SAME PLACE.

lNCAN DESCENT LAM P.

SPECIFICATION forming part of Letters Patent N0. 516,689, dated March20, 1894. Application filed December 30, 1893. Serial No. 495.279. (Nomodel.)

T0 all whom, it may concern.-

Be it known that I, GEORGE C. SWAN, of Brockton, county of Plymouth, andState of Massachusetts, have invented a new and useful Improvement inIncandescent Lamps, of which the following is a specification.

Myinvention relates to that class of incandescent lamps in which thereis a bulb, a stem of some material carryingthe leadingin wires and meansfor joining the stem with the bulb. It is obvious that in a lamp of thiskind, it is absolutely necessary for the life of the lamp that thereshall be no leak and that the expansion of those parts subjected to heatshall be substantially equal; that is to say, if the leading in wirestend to expand and contract, the material of which the stem is madeshould expand and contract to a like degree so that all the parts shallremain constantly in the same relation to eachother, and this is truealso of the stem and bulb. They must expand and contract equally unlessthey are connected by a material which can take up the differences ofexpansion and contraction, that is to say, which will expand andcontract to a degree substantially equal to each. This difference inexpansion and contraction exists between glasses of different makes andalso between glasses of different colors, and is one important item ofbreakage which has caused much trouble and expense in the lamp business,and it is this fault which my invention is designed to counteract.

I have shown in the drawings a lamp embodying my invention.

Figure 1 is the completed lamp. Fig. 2 is the bulb before the stem isinserted. Fig. 3 shows all the parts except the bulb. Fig. 4

'shows the stem in section and Fig. 5 the disk.

A is the bulb.

B is the stem through which pass the leading in wires b and C is thedisk.

The bulb A is made in any convenient manner and the stem is preferablymade of glass and is so constructed that the leading in wires are heldduring their entire length from contact so that they may be carried awayfrom the bottom of the bulb in opposite directions and hence anypossibility of short circuiting be obviated without the use of a cork orother such expedient. Such a stem can be used in my lamp because of themanner of connecting it with the bulb. It is obvious however, that thestem may be made of any material which Will fuse satisfactorily withplatinum or. such other metal as may be used for the disk, and hence bymy construction I am enabled to make my stem of a certain class ofoements or other materials, which are well known and are otherwise Veryuseful in lamp manufacture, bnt which cannot be successfully fused withglass. My disk however is made flatand is provided with a single holethrough which the stem, asa whole is inserted, and to the edges of whichthe stem is fused.

In manufacture the stem and disk are suitably connected and fusedtogether. I next place this structure s0 formed, within the bulb so thatthe outer edge of the disk rests against the bottom of the bulb, andthese two are thereupon fused together. The lamp is then completed inthe ordinary manner.

The mode of connecting the bulb and disk is of great value. Heretoforeit has been generally considered necessary to turn over the edge of thebulb, which weakens and thins the glass so that the bulb is more apt tosnap.

Various other means have been contrived for standing the leading inwires in the bulb and holding them in place, but none of them, so far asI know, are as simple or as satisfactory as that which I have described.The disk being flat, while it will expand and contract with the glass towhich it is fused, lying as it does between the outer surface of thestem and the inner surface of the bulb, and beingjoined to each atpractically right angles with its surface, it cannot work loose nor canit so yield as to cause any changein the cubical contents of the bulb,so that when the same lamp is once made, its contents always remainexactly the same and its work therefore is constant.

The lamp such as I have described is very simple and easy ofconstruction, being made preferably of materials of well known characterand easily procurable. It is extremely durable. I

I prefer to make the disk of platinum, but my invention consists inconnecting the stem with the bulb by a flat metallic disk having IOOsubstantially the same expansive quality as glass, the stem being inlike manner made of some material which has a like expansive qualitywith the disk, and being so constructed that the leadingin wires whichitcarries shall be insulated from each other and from the disk, so thatthe disk may tako up the variations of expansion and contraction betweenthe bulb and stem and thus prevent waste by IO breakage, and at the sametime so thatits general direction of greatest expansion and contractionshall be in the same general direction as the expansion and contractionof the bulb, namelyz-toward and from its axis. It [5 is apparent that inthis lamp when the filament is broken, the bulb can be broken so as toleave the disk carrying its leading in wires still fused together. A newfilament can be easily affiXed to the leading in wires and the zo stemand disk used a second time as a completed article for introduction intoa new bulb. Moreover it Will be seen that the stem is not a mere globuleof glass but is a support of suitable length carrying the leading inwires and supporting them for a greater part of their length, therebybringing the lower ends of the filament well within the bulb, so thatbut a small portion of the light from the filament is lost, and at thesame time forming amore perfectseal than when a short stem or button isused.

What I claim as my invention i5-- In an incandescent lamp, incombination with a bulb, a stem carrying two leading in wires embodiedtherein for a greater part of 3 5 their length, said wires beingprovided with a suitable filament attached thereto, anda flat metallicdisk lying substantially at right angles to the longitudinal axis of thebulb, the periphery of said *disk being fused to the inner surface ofsaid bulb, and the periphery of the stem being fused to the edge'of thehole through the disk, all as and for the purposes set forth.

In testimony whereot I have hereuntoset my hand this 14th day ofDecember, 1893.

V GEORGE C. SWAN.

Witnesses:

C. HERBERT MCLEAN, 'EDDISON RIETH.

